1. Field of the Invention
The present invention relates to a photoelectric-conversion device and particularly relates to a photoelectric-conversion device.
2. Description of the Related Art
Usually, an auto focusing (AF) sensor for detecting a focal point is provided in image pickup systems. In recent years, the AF sensors have been expected to be capable of detecting a focal point with higher speed and higher precision.
A solid-state image pickup device including a transfer system provided to transfer a signal which is output from a sensor-cell unit to a memory-cell unit has been disclosed in Japanese Patent Laid-Open No. 09-200614. According to Japanese Patent Laid-Open No. 09-200614, a plurality of the memory-cell units may be provided.
A focus-detection device including a frame memory provided to store the accumulation signal corresponding to each of regions that are obtained by dividing a line sensor into at least two regions and a frame memory provided to store the accumulation signal corresponding to all of the regions of the line sensor has been disclosed in Japanese Patent Laid-Open No. 2006-220684. According to Japanese Patent Laid-Open No. 2006-220684, the focal-point detection can be performed with high speed even in a case of a large amount of defocus.
However, no specific circuit configurations including a plurality of memory-cell units provided for a single sensor-cell unit and the operations thereof have been disclosed in neither of Japanese Patent Laid-Open No. 09-200614 and Japanese Patent Laid-Open No. 2006-220684.